This invention relates to a device for administering proton therapy to human patients as well as various improvements designed to increase safety, to improve and simplify process control, to enhance patient acceptability, and also to allow the device to be constructed to smaller dimensions; the invention also relates to an application of the device
Proton therapy, especially that intended for the treatment of cancers, is becoming increasingly important since it entails significant advantages in comparison with the photon-radiation therapy in widespread use.
Although equipment for administering proton therapy has been known since the mid-fifties in the U.S., up to now such therapies have been utilized worldwide only at a few centers such as research institutions. This circumstance is due first to the fact that proton accelerators required are still quite expensive, and secondly to the fact that the proton therapy equipment necessary for administering an efficient and safe therapy is quite large and complex. The first and only purely hospital-based proton therapy device is located in the U.S. at the Loma Linda University Medical Center in California. Additional units are in the process of being put into operation in Boston (U.S.) and Kashiwa (Japan).
Unlike the above device at the Loma Linda University Medical Center in which the proton therapy is performed using a so-called scattering method, a proton therapy device was developed at the Paul Scherrer Institute in Wxc3xclingen, Switzerland, which utilizes the so-called spot-scanning method. In this connection, reference is made to the article by Eros Pedroni et al. in Med. Phys. 22 (1), January 1995, pages 37-53 with the title xe2x80x9cThe 200-Mev Proton Therapy Project at the Paul Scherrer Institute: Conceptual Design and Practical Realization.xe2x80x9d This article refers to the fundamental principle of the above-mentioned spot-scanning method and to a device described using the term xe2x80x9cgantry,xe2x80x9d with which device proton therapy has now been administered to patients for about three years . Although the outside dimensions of the device at the Paul Scherrer Institute were able to be reduced relative to the device at the Loma Linda University Medical Center by using the so-called spot-scanning method, this device still has a diameter of about 4 m, and has the additional disadvantage that access to patients during treatment is unsatisfactory. A detailed description of the device at the Paul Scherrer Institute may be dispensed with by citing the above reference in the literature, which reference is an integral part of the present patent application.
In European Patent Applications EP 0 864 337 and EP 0 911064, similar arrangements for treating a patient by proton therapy are described, which are partially based on the device developed at the Paul Scherfer Institute or describe similar or the same treatment methods.
The preferred position for a patient is the supine position so as to preclude any deformation of the organs during treatment. Therapy must therefore allow accessibility from all sides and encompass the entire human body; for this reason, the generally known proton therapy devices, including that at the Paul Scherrer Institute, are designed so that the entire proton beam guiding device housing is rotatable 360xc2x0 about a central axis around the so-called patient table, with the result that the device may have a diameter of between 4 and 12 meters. Especially when treating a patient from below, the proton beam guiding device must be moved under the patient table, or the patient table must be raised to a position several meters above the actual level of the working base. The resulting specific disadvantages may also be found in the above-cited literature reference on page 49 in chapter IV, D4 which cites the problems entailed by raising the patient table in this way. This positioning process is critical, and in the event the device experiences an accident during treatment, a special crane device is required to extract or manage the patient. While this disadvantage may be alleviated by providing a relatively deep shaft under the patient table, this approach creates a risk of accidents, such as the person treating the patient falling Into this shaft.
The object of this invention is thus to propose measures by which the operation of proton therapy may be simplified and made safer, and in which preferably the outside dimensions of the device may be reduced. This object is achieved by the proton therapy device or apparatus of the invention, and by means of a method for treating a patient according to the invention using the proton therapy apparatus.
The invention proposes that a proton beam guiding and control device, or a proton beam guiding device housing located in the treatment arrangement, not be rotatable by a full 360xc2x0 around a patient table, unlike the xe2x80x9cgantryxe2x80x9d of the Paul Scherrer Institute, described in the literature, but that the rotational movement be limited to approximately 270xc2x0. Here the rotation occurs essentially about a horizontal axis of rotation, in which axis of rotation generally a controllably movable patient table is located in the starting position. This limitation to 270xc2x0 results in a region through which the beam guiding and control device is not freely movable, in which region the patient table is freely movable and always readily accessible. It is this accessibility to the patient table in particular which represents an essential improvement provided by this invention since the person providing treatment may always access the patient without danger or obstruction.
The result of this preferred arrangement of the proton beam guiding and control device in which the device is rotatable starting from the horizontal plane running essentially through the axis of rotation both upwards and downwards by approximately 135xc2x0 about the axis of rotation, or from xe2x88x9290xc2x0 to +180xc2x0 from the vertical, is that the patient table is readily accessible from the opposite side. The patient table is thus freely movable within the above-mentioned horizontal plane or within a horizontal plane designed to run nearly parallel to this planexe2x80x94for example, specifically rotatable by at least 180xc2x0 about an axis which runs essentially through the isocenter of the proton beam guiding and control device. The isocenter is formed on the one hand by the proton beam exiting the proton beam guiding and control device, and on the other hand by the axis of rotation about which this device is rotatable.
The result of this arrangement according to the invention is first of all, as already mentioned, that the patient table is always readily accessible, and secondly that despite this accessibility treatment of the patient from all sides is possible since first of all treatment both from above and below is ensured, as is treatment from both sides, the treatment being enabled by rotating the patient table by 180xc2x0.
Preferred variant embodiments of the arrangement according to the invention are characterized in the dependent claims.
To provide a fuller understanding of the invention, an example of a proton beam treatment device according to the invention is described in more detail based on FIGS. 1-3.